Hydrocarbons in an undersea reservoir lying at the bottom of a deep sea (over 500 meters) are commonly produced by an installation that includes risers for carrying the hydrocarbons up from the sea floor to a production vessel that stores the hydrocarbons. The connections to the sea floor can also include flowlines for water injection, gas lift, gas export, and umbilicals, and also mooring lines that moor the vessel. At times the vessel must sail away from a location over the region of the reservoir where the risers and mooring lines are located, as when a storm is approaching, or to carry the stored hydrocarbons to another station, or for another purpose. For this reason, the installation commonly includes a connection buoy, or buoyant connector that is connected to the upper ends of the risers and the upper ends of the mooring lines, and that is in turn, connected to the vessel in a manner that allows the connector to be disconnected and reconnected. When the connector is disconnected from the vessel, the connector sinks to a position that is at least 25 meters under the sea surface so the connector lies under most or all of the wave action zone.
When the vessel returns to the production installation, the connector must be raised and connected to the vessel by personnel on the vessel and/or divers. The less massive the connector, the easier it is to manipulate and move during disconnection and reconnection. The present invention is directed largely to making such installations so the connector is of minimum mass and volume and therefore easier to move, and so the connector is moved a minimum distance. The installations are used primarily for the production of hydrocarbons, but are useful wherever large quantities of hydrocarbons are to be transferred.